bret

bret

Well Known Member
Ok, so a friend of mine was solo bottom skin riveting the wing and during the act of bucking and reaching one of the back rivets the bucking bar slipped out of his finger tips, fell and dented the top skin out. He was wonder if there was a good way to repair this dent?............Ok ok it was me.
 
That's why I do them upright in the wing cradle. But seriously, can you post a picture? It probably needs to be bumped inward & filled.
 
Taking a pic was totally deceiving and depressing. It looked like it was protruding 1/4" so I got a straight edge and measured it. Interestingly I could only get a .010 feeler gage under one side...protruding .005 thousands?, how thick is filler primer? I think the reflectivity of the skin makes it look much worse. So do I risk making it worse or leave it?
 
You did say "bottom skin", didn't you?

So, who's gonna crawl under the airplane anyway? Put a bucking bar on the inside, lightly tap what you can and then forget about it:)

Best,
 
Bret:

Are you going to paint your airplane or have it painted? If you can deal with it being there, just leave it. Your painter will turn the "outtie" into an "innie" and fill it. Once the metal is stretched there's no undoing it. Ask me how I know.
 
Car dent repair guy

I recently had a friend over to my shop who makes his living fixing dents on cars - say, after hail storms. Says they typically can fix 1000 dents in a day. Anyway, I had a few dents here and there and wanted to see if he could fix them before I pushed them in and filled them. Interestingly, most dents on cars are "innies" while most dents (but not all) on my plane were "outies". Outies are easier. Nothing serious, but they would need to be dressed up one way or another before paint. Bottom line, unless the metal was creased, he worked out all the dents until you couldn't see them if you didn't know they were there. It's very impressive to watch him work, very light, gentle taps and pushes. You might look into a local dent fixer, they are every where and can usually tell you by looking at it whether they can do anything with it.
 
Jamie said:
Once the metal is stretched there's no undoing it. Ask me how I know.
Click to expand...

That is absolutely not true. You can shrink aluminum back up, that's how you build complex 3d shapes with aluminum. You can't always stretch, sometimes you need to shrink.

Anyway, for more information go checkout the master of sheet metal:

http://tinmantech.com/

schu
 
My hangar partner wound up with a pretty good sized "innie" after an encounter with a hawk. One of the local airport denizens claimed he could pop it out by working it carefully with a file. It was one of those "I gotta see this" moments. I thought he was going to file away metal but he didn't- he hammered with it. The dent was at least 3/8" deep on the leading edge of the wing, probably in an area the diameter of a golf ball. He didn't quite get all of it out, but it's almost gone. That without ever getting inside the wing (which would've been difficult, because it's the fuel tank). I would not have believed it could be done like that if I hadn't seen it myself. Still not ready to try it on something I cared about, though.
 
Dent removal....

I've seen this guy at work. Best I can tell, it's black magic. I mean, how can magnetism pull dents out of aluminum? It does:

http://fluxtronic.com/sample.php

Probably a little pricey for a homebuilt, but when a typical jet leading edge is over $60K, he has plenty of room for pricing.
 
Jamie said:
Once the metal is stretched there's no undoing it. Ask me how I know.
Click to expand...
I have to disagree. I've successfully dressed "outies" into flat surfaces on both aluminum and sheet metal using a flat hammer and a sturdy flat surface like a bucking bar or an anvil (depending on where I had the dent). You can shrink metal just like you can stretch it, with small taps, carefully placed.
 
Aluminum is a nonferrous metal, I don't see how an electro magnet is going to pull a dent out of the skin.
 
Love my wing dent

I used to pay my son's a few cents a rivet to help me buck rivets..(yes I am cheap and they were young and it was a great way to spend time with them while workng on the plane) Anyway, one day my son lets the bucking bar slip and I end up with a big smiley face on the bottom of my wing....I was so pissed......now, years later, I am embarassed about getting mad at my son at that time. With all of my son's grown and out of the house, when I go to the plane and see that smiley face on the bottom of my wing it puts an RV grin on my face remembering fondly those days in the basement putting in rivets with my sons.....Some dents in airplanes are treasures.
 
bret said:
Aluminum is a nonferrous metal, I don't see how an electro magnet is going to pull a dent out of the skin.
Click to expand...

My guess is that it works like the Thomson ring launcher, just that instead of switching the magnetic field on you switch it off. I'll try to explain the principle. If you have an electric conductor in a magnetic field and change the magnetic field, a current is induced in the conductor such that this current tries to "keep the magnetic field alive". So for a brief moment this electric conductor will become an electromagnet. Now to the dent-pulling device. It's basically a coil, i.e. an electromagnet. Turn the magnet on, put it close to your dent, switch the magnet off. Now the magnetic field collapses (this takes a short time), meanwhile a current is induced in the dented aluminum sheet which turns the aluminum into an electromagnet itself (also just for a short time). For a moment we have now two magnets: The field of the coil isn't completely gone yet, and the dented aluminum is a magnet itself, being attracted to the coil. Voila, the aluminum is pulled outwards.

Have a look at the first video on this site http://www.chemgapedia.de/vsengine/...g/magnetfeld/induktion/induktion07.vscml.html
The description is in German (sorry), but it's a nice show experiment where you can see what happens with an aluminum ring if you turn the electromagnet on and off. Turning the magnet on results in a repulsive force, turning it off in an attractive force. Of course any other electric conductor will work, too. Just for fun click on the second video -- it shows what happens if you use a stronger electromagnet and turn it on.
 
That is the first time in my life that I have ever seen a nonferrous metal move with a magnetic force, I always thought that magnets work on iron core material. I still don't get it but hey, if it works it works.
 
You must log in or register to reply here.